The nuclear receptor CAR (NR1I3) regulates serum triglyceride levels under conditions of metabolic stress.
The nuclear receptor constitutive androstane receptor (CAR) (NR1I3) regulates hepatic genes involved in xenobiotic detoxification as well as genes involved in energy homeostasis. We provide data that extend the role of CAR to regulation of serum triglyceride levels under conditions of metabolic/nutritional stress. The typically high serum triglyceride levels of ob/ob mice were completely normalized when crossed onto a Car(-/-) (mice deficient for the Car gene) genetic background. Moreover, increases in serum triglycerides observed after a high-fat diet (HFD) regime were not observed in Car(-/-) animals. Conversely, pharmacological induction of CAR activity using the selective mouse CAR agonist TCPOBOP during HFD feeding resulted in a CAR-dependent increase in serum triglyceride levels. A major regulator of hepatic fatty oxidation is the nuclear receptor PPARalpha (NR1C1). The expression of peroxisome proliferator-activated receptor alpha (PPARalpha) target genes was inversely related to the activity of CAR. Consistent with these observations, Car(-/-) animals exhibited increased hepatic fatty acid oxidation. Treatment of mice with 1,4-bis[2-(3,5-dichloropyridyloxy)]benzene (TCPOBOP) significantly decreased expression of PPARalpha mRNA as well as Cyp4a14, CPT1alpha, and cytosolic Acyl-CoA thioesterase (CTE) in the liver. These data have implications in disease therapy such as for diabetes and nonalcoholic steatohepatitis (NASH).
Maglich
Jodi M
JM
Metabolic Pathways, GlaxoSmithKline, Research Triangle Park, Durham, NC.
Lobe
David C
DC
Metabolic Pathways, GlaxoSmithKline, Research Triangle Park, Durham, NC.
Moore
John T
JT
Metabolic Pathways, GlaxoSmithKline, Research Triangle Park, Durham, NC. Electronic address: John.T.Moore@gsk.com.
D000818:Animals; D001483:Base Sequence; D000090702:Constitutive Androstane Receptor; D017931:DNA Primers / Q000235:genetics; D004041:Dietary Fats / Q000008:administration & dosage; D005227:Fatty Acids / Q000378:metabolism; D050356:Lipid Metabolism; D008099:Liver / Q000187:drug effects / Q000378:metabolism; D008297:Male; D051379:Mice; D008810:Mice, Inbred C57BL; D018345:Mice, Knockout; D008820:Mice, Obese; D020411:Oligonucleotide Array Sequence Analysis; D047493:PPAR alpha / Q000235:genetics / Q000378:metabolism; D011725:Pyridines / Q000494:pharmacology; D012333:RNA, Messenger / Q000235:genetics / Q000378:metabolism; D018160:Receptors, Cytoplasmic and Nuclear / Q000819:agonists / Q000172:deficiency / Q000235:genetics / Q000378:metabolism*; D013312:Stress, Physiological; D014157:Transcription Factors / Q000819:agonists / Q000172:deficiency / Q000235:genetics / Q000378:metabolism*; D014280:Triglycerides / Q000097:blood*
D000090702:Constitutive Androstane Receptor; D017931:DNA Primers; D004041:Dietary Fats; D005227:Fatty Acids; C000716328:Nr1i3 protein, mouse; D047493:PPAR alpha; D011725:Pyridines; D012333:RNA, Messenger; D018160:Receptors, Cytoplasmic and Nuclear; D014157:Transcription Factors; D014280:Triglycerides; C028474:1,4-bis(2-(3,5-dichloropyridyloxy))benzene